Tandy 1000 HX - Page 55

• TANDY COMPUTER PRODUCTS •
50
Bit4 = 0 & OPERATION CONTROL WORD 2
Bit3 = 0 BitO - 2: Determine the interrupt level acted on
when the SL bit is active
Interrupt Level =01234567
BitO (L0): 01010101
Bitl (Ll): 00110011
Bit2 (L2): 00001111
Bit5 - 7 Control Rotate and End of Interrupt
modes
B7
0
0
1
1
0
1
1
0
B6
0
1
0
0
0
1
1
1
B5
1
1
1
0
0
1
0
0
Non-specific EOI command
Specific EOI command
Rotate on non-specific EOI command
Rotate in Automatic EOI Mode (set)
Rotate in Automatic EOI Mode (clear)
*Rotate on Specific EOI command
*Set priority command
No operation
End of Interrupt
End of Interest
Automatic Rotation
Automatic Rotation
Automatic Rotation
Specific Rotation
Specific Rotation
*LO - L2 are used
Bit4 = 0 &
Bit3 = 1
OPERATION CONTROL WORD 3
BitO - 1:
Bitl BitO- Read Register Command
0 0 - No Action
0 1 - No Action
1 0 - Read IR Register on next IOR* Pulse
1 1 - Read IS Register on next IOR* Pulse
Bit2 =0: No Poll Command
= 1: Poll Command
Bit5 - 6:
Bit6 Bit5- Special Mask Mode
0 0 - No Action
0 1 - No Action
1 0 - Reset Special Mask
1 1 - Set Special Mask
Bit7 = 0